With an increased focus on environment and health, there is an interest and/or a need to find suitable reagent replacements of petroleum-based reagents of toner.
As is known in the electrophotographic process, during copying, an electrostatic latent image is formed on a photoreceptor made of photoconductive material, which latent image is transferred onto a receiving medium or substrate, such as, a paper or a sheet, and then the image is fused or fixed to the medium using, for example, heat, solvent or pressure.
Heat melting processes have been widely used for fixing transferred toner images and are classified largely into two processes: contact processes and non-contact processes. Contact processes are superior in thermal efficiency and thus allow high-speed fixing. However, heat-roll fixing processes have some drawbacks, such as, adhesion of the image to the photoreceptor and poor adhesion of toner on the medium.
One approach for addressing those shortcomings is to employ toner binder resin that, for example, has a lower glass transition temperature (Tg) to facilitate more rapid solidification. However, many such toilers have a drawback in aggregating or caking during storage or in an end user device. Also, such toners can adhere to the photoreceptor or to the fuser, called, “offset,” where the toner particles are passed on to subsequent media.
Another approach is adhering fine particles, such as, colloidal silica, alumina or titania to the surface of toner particles for improvement in blocking resistance and flowability. However, the fine particles, even if subjected to heat treatment or the like for adhesion to the toner particle surface, often are released from the toner particle surface, negatively affecting the photoreceptor, in particular one having a surface coated with an organic polymer or the like.
Various waxes are used as a fixing aid in toner. However, the addition of too much wax will cause poor toner flow properties.
In a heat-roll fixing process, curling of a transfer medium, such as, paper, around a fixing or fusing roll after fixing can be prevented by a stripper finger placed in the fixing roll unit (heating unit). However, with the recent trend to higher speed copying machines, stress applied at that site process is larger, leading to more frequent image defects, such as, stripper finger artifacts present on an image.
Exfoliation or local detachment of the surface layer of fixing or fusing units due to inadequate release and excessive application of local stress, such as, toner or aberrant stripper finger operation, further causes fatal defects in the surface of the fixing units (heating unit and pressurizing unit) surface. For example, the surface layer of the heating unit is usually coated with a layer of polymer superior in release properties, such as, a silicone or fluorocarbon resin for prevention of toner particle adhesion. If that layer is damaged, toner components remain on the surface of the heating unit. That causes offset wherein toner is retransferred onto an unintended printing face.
Hence, there remains a need to obtain toner with good fusing performance to enable, for example, faster printing speeds. There also is a need to have toner that is more environmentally friendly.